Golf Course Management

MAY 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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64 GOLF COURSE MANAGEMENT 05.18 sects. Simply delaying the application of pesti- cides (insecticides) while small and vulnerable colonies of honey bees and bumble bees are recovering from winter stress can dramatically reduce the likelihood of potential exposure to toxic insecticides. Turfgrass managers can also minimize the potential risk of pesticide exposure to pollinators by applying pesticides only in the early morning or early evening when most pollinator species are not actively foraging. Making pesticide applications dur - ing these time periods can also mitigate the potential risk of spray (pesticide) drift to areas that likely support high populations of forag - ing pollinators (1). Product formulation e extent to which a pesticide is hazard- ous to pollinators is also largely affected by the formulation of the product, not just the ac - tive ingredient (11). Pesticides used in turf are available in various formulations, including liquid sprays and granules. ese formulations vary in their potential to affect pollinating in - sects (2). A research study compared sprayable to granular formulations of neonicotinoids when both were applied to flowering weeds in turf. Results showed that the risk of pes - ticide exposure to pollinators was lower with granular formulations than with sprayable formulations (7). Although both the liquid and granular products are systemic, the gran - ular formulation is less likely to contaminate flowering portions of blooming plants. Even though applying liquid pesticides to bloom - ing or flowering weeds poses a greater risk of pesticide exposure to pollinators, this negative interaction can be avoided by applying post- treatment irrigation or removing flowering weeds by mowing (7). Post-application turf care Product labels often require post-treat- ment irrigation, especially for management of below-ground insects such as white grubs. Irrigation can also remove or dislodge pesti - cide residues from pollinator foraging zones of treated plants and dilute the active ingredient concentrations, thus reducing potential haz - ards to pollinating insects (2,6). It is suggested that irrigation — particularly in the morning — may dilute residues of insecticides present in dew or guttation droplets that frequently accumulate on turfgrass (8). development of rational, science-based recom - mendations for best management practices that promote healthy turf while conserving and enhancing pollinator health. BMPs for implementing chemical controls in turfgrass Turfgrass managers have been imple- menting integrated pest management (IPM) practices for decades to maximize pest man - agement efficiency and efficacy while reduc- ing potential adverse or non-target effects on natural enemies and beneficial organisms (4). Turfgrass managers can employ similar prin - ciples to mitigate potential risks to pollinators. First and foremost, merely following the pesti - cide label and ensuring that pollinators are not directly exposed to pesticide residues can min - imize potential negative impact to pollinators. Other best management practices, including action before, during and after pesticide ap - plications, are often simple and inexpensive. Pre-application considerations Applying insecticides directly to flowers has resulted in pollinator kill, notably when in - secticide was applied to blooming linden trees in Oregon in 2013 (10). In the turf ecosystem, flowering weeds are quite common and attrac- tive to various pollinating insects (7). Mowing off the flower heads of weeds like white clover, dandelion and others before pesticide (insecti - cide) application is recommended in order to avoid the issues associated with direct floral contamination. Evaluation of nectar in turf - grass weed flowers treated with neonicotinoids suggests that if new flowers regrow in treated areas, the residues detected in the new flowers are below the levels thought to be hazardous or harmful to pollinators (8). Consequently, where turfgrass weeds are mowed regularly, application of pesticides (including neonic - otinoids) does not pose a prolonged systemic hazard to bees. Timing of pesticide applications Turfgrass managers should be mindful of the timing of pesticide applications. Timing can determine the likelihood of pollinator ex - posure to pesticides, especially insecticides. Most pesticide applications, including insec - ticides, are applied preventively from March through June (4). Unfortunately, such pre - ventive application timings coincide with the blooming of flowering weeds that frequently attract numerous species of pollinating in - Preventive pesticide applications often coincide with blooming of flowering weeds that attract pollinating insects. Mowing blooming weeds to remove flower heads before application of liquid pesticides will significantly reduce the possibility of harm to pollinators.

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